SIRIUS thermal overload relay, S0 frame, CLASS 10
The Siemens 3RU1126-1JD0 is a SIRIUS-branded thermal overload relay in the S0 frame size, designed for contactor mounting. It provides motor protection with a CLASS 10 trip characteristic, meaning it will trip within 10 seconds at 7.2× the set current — the standard for standard-start induction motors driving pumps, fans, and conveyors where the rotor doesn't stall under load. Rated for AC-3 duty up to 690 V, this relay handles the switching stresses of squirrel-cage motors. The front face carries an IP20 rating, so it's touch-safe once installed in an enclosure but not suitable for washdown environments. It carries ATEX certification (DMT 98 ATEX G 001), confirming suitability for explosive-gas atmospheres — a key differentiator for chemical, oil-and-gas, or grain-handling installations where standard overload relays would not be permitted.
Mounting and integration
Mounts directly onto a Siemens contactor (S0 frame) — no separate DIN-rail bracket needed. The mounting position allows rotation of ±135° on a vertical surface and tilting of ±45° front-to-back, giving panel builders flexibility in tight layouts. Dimensions are 97 mm high, 45 mm wide, and 96 mm deep — a compact footprint that fits standard S0 contactor spacing. Side clearance of 6 mm is required for heat dissipation; zero clearance needed above, below, forward, or backward. Main circuit connections use screw-type terminals accepting 2× (0.5…2.5 mm²) solid or 2× (16…12 AWG) stranded. Finely stranded conductors with ferrules can be 2× (0.5…1.5 mm²). The auxiliary contact block is not integrated (0 auxiliary contacts), so an external block is needed if you require status feedback.
Environmental and electrical ratings
Operates from -20 to +70 °C, stores and transports from -55 to +80 °C. Withstands 100 % relative humidity during operation and shock loads of 8g for 10 ms — robust enough for machine-mounted applications near vibrating equipment. Power dissipation at AC in hot operating state is 6.6 W total, or 2.2 W per pole. Surge voltage resistance is rated at 6 kV. Maximum operating altitude is 2 000 m without derating. Auxiliary contact ratings: 1 A at 24 V, 3 A at 120 V, 2 A at 230 V, 1 A at 400 V — all AC. For DC control circuits: 0.22 A at 110 V or 125 V, 0.11 A at 220 V.